1. Field of Invention
The present invention relates to an electric motor in which an outer ring yoke portion and an inner ring magnetic pole portion are separately formed, a rotor is inserted into the inner ring magnetic pole portion, and coils are wound on the inner ring magnetic pole portion.
2. Description of Prior Art
FIGS. 28 and 29 show a conventional electric motor. FIG. 28 is a plan view showing a stator of the motor, and FIG. 29 is a perspective view of the motor. In a conventional motor as shown in FIG. 28, slots 1 are formed at an inner circle of an iron plate 2. A plurality of such iron plates 2 are stacked so as to form a stator 3. Coils 4 are wound between the slots 1 of the stator 3 by the insert method. A U-shaped insulating wedge is disposed in each of the slots 1 (for example, see Unexamined Japanese Utility Model Publication (Kokai) Sho-56-141576) .
As shown in FIG. 29, after leads 4a are connected to respective terminals of the coils 4 on the stator 3, the stator 3 is located in a housing (not shown), and the leads 4a are connected to a power supply cord (not shown) (for example, see Examined Japanese Patent Publication (Kokoku) Sho-59-32980).
FIGS. 30 and 31 show another conventional electric motor. FIG. 30 is a perspective view showing an outer ring yoke portion of the motor, and FIG. 31 is a perspective view showing a terminal cover of the motor of FIG. 30. In a conventional motor as shown in FIG. 30, a terminal holder 67 is mounted on an outer ring yoke portion 5. Terminals of coils 26 are connected to terminals 68 on the terminal holder 67. Thereafter, a terminal cover 69 on which leads 47 are mounted is attached to the terminal holder 67, so that the terminals 68 and the leads 47 are connected to each other (for example, see Unexamined Japanese Utility Model Publication Sho-57-115545).
In the above-mentioned conventional motor shown in FIGS. 28 and 29, the coils 4 are inserted into the slots 1 by the insert method. Therefore, it is necessary to provide the coils 4 with an extra length (slackening) in addition to the length needed for winding the coils 4 between the slots 1. As a result, the necessary length of the coils 4 should be made larger, and hence the amount of conductors for the coils becomes large, which deteriorates the characteristics. In some cases, the coils 4 may be bulged out of the slots 1, or ends of the coils 4 may be unbraided. In such cases, it takes a long time to perform working processes such as shaping, coil binding, and varnishing. Moreover, such working processes are difficult to be mechanized.
Moreover, the connections between the coils 4 and the leads 4a, and thermal fuses (not shown) and the coils 4 are manually performed by soldering or the like which requires skill. Therefore, there exists another problem in that the connecting work requires man power and takes a long time.
When the U-shaped insulating wedges are to be inserted into the slots 1, the shape of the wedges makes the insertion difficult. Because of this poor workability, it is difficult to automatically perform the insertion. Moreover, in some cases, the coils 4 may be bulged out from the gap formed between the wedge and the stator 3. Since it is difficult to automatically detect this failure, there arises a problem in that it is necessary to perform the detection by visual observation.
In another conventional motor shown in FIGS. 30 and 31, the terminal holder 67 and the terminal cover 69 are separately formed, thereby causing a poor working efficiency in assembling the motor. Therefore, there is a problem in that the motor cannot be automatically assembled.